N/A *NON-flycut* Stock 302 short block H/C/I Track experience

[Pure Stock]

I've read on the calculators' website that the hp is rwhp...

It would be pretty dumb to list FWHP since most everyone's % drivetrain loss is different. However...that's just my thinking...doesn't mean that rwhp is actually what they calculate.

Supposedly those calculators are fairly accurate.

I can't follow that logic one bit. 430-374= 56 h.p. The two calculators I've been using since 1997 on multiple cars and combinations puts FWHP in the range of 430-440 and RWHP in the range of 370-380. I cannot see RWHP jumping from roughly 375 to 430 on track conditions alone. Especially when the D.A. was around 650' above on the 125.22 run.

[Rodeheaver's]

you guys deff don't want to get into a calculating battle with purestock, i bet that he know what every car that went to keystone in the last 3 years has gone in the 1/4...

[Martin0660]

I typically really trust the Wallace calculators. The problem is, when you get real efficient on ET, they get off on the estimate. I have a similar problem. I typically trust the MPH method as true, the ET method is shakey.

Your HP computed from your vehicle ET is 458.57 rear wheel HP and 509.52 flywheel HP.
Your HP computed from your vehicle MPH is 389.61 rear wheel HP and 432.90 flywheel HP.

When you get to that level, a better estimate is to calculate based on 60' as a cross check....

Your HP computed from your 60 Foot Time of 1.454 at Weight of 2825 pounds is 449.94 HP.

On the other hand, this calculator is usually prety good at predicing a 60' time based on ET, and it misses for yours, and i'm not sure how that works.

Estimated 60 Foot Time: 1.473956 seconds.

All of this assumes a correct vehicle weight. Are you sure on that race weight? Thats the only thing I can see that would account for the errors in the calculations. For sure it was good air you were racing in.

Bob Myers

[somethingclever]

I can't follow that logic one bit. 430-374= 56 h.p. The two calculators I've been using since 1997 on multiple cars and combinations puts FWHP in the range of 430-440 and RWHP in the range of 370-380. I cannot see RWHP jumping from roughly 375 to 430 on track conditions alone. Especially when the D.A. was around 650' above on the 125.22 run.

My logic is this.....

The calculator should calculate a RWHP number because that is how much hp you actually use.

If i have a car that has 10% drivetrain loss and runs 125 mph in 2825 lb car, then i'm going to get XXX hp from the calculator.

If I have a car that has 20% drivetrain loss and runs 125mph in 2825lb car, then i'm going to get the SAME hp from the calculator *IF* the calculator give hp in FWHP. But that's just not true, the RWHP is the same for both cars, but the FWHP is going to be different.

[fastfox91]

i have run alot of peoples numbers through these online dyno's take gmkiller for instance
if u punch in his numbers numbers in at http://www.bid2race.com/calcs/powerfrommph.html
3450lbs which is im assuming race weight and 123mph u get 501hp at the wheels his car made 505hp on a dyno
take another online dyno
http://bbs.hardcore50.com/calc/index.php?mode=hpfrompw
punch those same numbers in and u get 495 hp which is still within 10hp
and heres another
http://www.prowleronline.com/onlinedyno.html
same numbers input u get 501.05668082739095
which is still real close to his real dyno numbers

if u run the numbers from your car they arent close at all i get like 421 to 433 to but i figure with the tranny that is in your car the and the great 60fts and lots of track time might be what throws these numbers off
by the way sorry gm killer your numbers just happen to be right there when i was thinking about this lol!

[fastfox91]

here was what i got when i punch my numbers in which if they are close i would be tickled to death 626.35 my car has never been on a dyno so have no idea what it would really be but that would be awesome if that is what it is

[Pure Stock]

I typically really trust the Wallace calculators. The problem is, when you get real efficient on ET, they get off on the estimate. I have a similar problem. I typically trust the MPH method as true, the ET method is shakey.

Your HP computed from your vehicle ET is 458.57 rear wheel HP and 509.52 flywheel HP.
Your HP computed from your vehicle MPH is 389.61 rear wheel HP and 432.90 flywheel HP.

When you get to that level, a better estimate is to calculate based on 60' as a cross check....

Your HP computed from your 60 Foot Time of 1.454 at Weight of 2825 pounds is 449.94 HP.

On the other hand, this calculator is usually prety good at predicing a 60' time based on ET, and it misses for yours, and i'm not sure how that works.

Estimated 60 Foot Time: 1.473956 seconds.

All of this assumes a correct vehicle weight. Are you sure on that race weight? Thats the only thing I can see that would account for the errors in the calculations. For sure it was good air you were racing in.

Bob Myers

The race weight could be anywhere from 2810 to 2830 IMO. I have not weighed it in it's current state. Although, the last time I weighed it, it came in at 2860 at the truck stop on a CAT scale. Using a bathroom scale I subtracted from the weight everything I eliminated.

[Pure Stock]

My logic is this.....

The calculator should calculate a RWHP number because that is how much hp you actually use.

If i have a car that has 10% drivetrain loss and runs 125 mph in 2825 lb car, then i'm going to get XXX hp from the calculator.

If I have a car that has 20% drivetrain loss and runs 125mph in 2825lb car, then i'm going to get the SAME hp from the calculator *IF* the calculator give hp in FWHP. But that's just not true, the RWHP is the same for both cars, but the FWHP is going to be different.

The formulas I employ require the user to estimate a percentage of driveline loss. Usually 15%-18% (which is subjective at best) Now if I plug in your estimated number of 430 to the wheels and multiply that by a 17% loss (heavy tko trans.) I find that I am making 503.1 FWHP. Take 503.1/301.59 c.i.d.that equals 1.6681587 FWHP per c.i.d. This is where I begin to lose site of that line of thought you presented. At 9:1 C.R., and a small hydraulic roller that has a relatively low peak power, I cannot see that kind of power being generated. I have factual/objective dyno data that reinforces my claims. Now, there can/will be some fluctuation in power output manipulated by weather conditions, but a swing of 56 h.p. is highly unlikely. Perhaps if I would have dyno tested in Denver and raced back here.

I understand what you are saying about RWHP propeling a vehicle to a certain MPH and the two vehicles having different FWHP ratings. Many factors influence the fluctuations and need to be considered. My point is this, the formulas I use are fairly accurate when the weight variable is accurate. Perhaps you are using a formula that calculates FWHP?? If you are still in disagreement with my explanation, explain to me how I achieved a 56 hp gain from the dyno to cecil.

[yeahloh95]

http://www.youtube.com/watch?v=NctjyB4Ja7k



here you go guys
http://www.youtube.com/watch?v=n3PZO4eWNIo

[04yellowcobra]

Awesome runs!!

[somethingclever]

If you are still in disagreement with my explanation, explain to me how I achieved a 56 hp gain from the dyno to cecil.

56hp?...doubtful
30hp?...not a stretch

For paper racing purposes –

Density of air @ 80 F - .0737 lb/ft^3
Density of air @ 40 F - .0790 lb/ft^3

difference – 7%

If you dyno’d 375 rwhp in an 80 deg dyno room, and then went to the track on a 40 deg day, your hp at the track would have been 375/.93 = 403rwhp from the temp difference alone. Your MAF would have added the necessary fuel to keep the a/f ratio the same.

Estimating a ram-air effect of traveling 125mph down the 1320’ – the velocity pressure can be described as qz = .00256*(v^2) where qz is given in lb/ft^2

qz = .00256*(125^2) = 40 conveted to psi = .278psi

If you make 403rwhp/14.7psi = 27.41hp/psi

Add 14.7+.278 = 14.98psi

14.98*27.41 = 410rwhp

It would be interesting to put a precise pressure gauge in the inlet track pre-maf to see what the amt really is. It just might be even more.

Do I think you have 430rwhp? No
Do I think you were making significantly more hp than 375 on sat? Yes
Do I still think calculators are pretty accurate? Not as much

[gmkillr]

Good thing we dont race these calculators or there would be alot of dissapointed people out there. Thats why we actually race the car. Who cares what the dyno or calculator says....
Just worry what your timeslip says....

[SonofaBish]

The formulas I employ require the user to estimate a percentage of driveline loss. Usually 15%-18% (which is subjective at best) Now if I plug in your estimated number of 430 to the wheels and multiply that by a 17% loss (heavy tko trans.) I find that I am making 503.1 FWHP. .

I've never used the calculators you guys are speaking of, but your math is wrong right here... you don't multiply 430 by 1.17 as you've done here... you divide 430 by .83 and you will get an even higher FWHP number (518).. which will even futher inflate the HP number that you disagree with...

Ok, sorry, i'm an actuary, i see things like this.. just wanted to clear that up for you so you don't make that mistake in the future... it CAN throw the numbers off by quite a bit .. in this case, only 15hp

[Martin0660]

Here is a good calculator for factoring air.

http://wahiduddin.net/calc/calc_hp_abs.htm

Bob Myers

[sutyak]

Excellent!!!!!!!!!!
THIS is what I love to see my friend!
And this is what the 500whp FWD guys running 13s will never understand!

[Pure Stock]

...

[cobra232]

that's pretty awsome times man.

there are alot of variables.

Matt Neuharth's Turbo 3.8 SN95 made about 600rwhp and did 10.25@125 and i believe his car is about 3100lbs.

traction and torque curve are huge factors. if you can hook with good midrange torque and great highend then you will trap fairly low ET high MPH. if you can't hook all that well and torque is low on the bottom and mid then your times will be the same even though you have much higher peak HP.

the calculators are decent guidelines but shouldn't be followed like a sliderule

[billyNOTnice]

This thing sounds like your not even using a clutch.... As far as all the conflict goes, i'd like to see what your car weighs on a scale currently in race trim. Either way, great videos, nice times, and killer picture you posted up in that other thread... I love it.